Overview

Brief Summary

Biology

While information on the biology of this particular species is lacking, it is likely to be similar to that of other seahorses (Hippocampus species). Seahorses are ambush predators that wait in the water until a prey, such as a small crustacean, tiny, young fish, or other invertebrate, passes close by its mouth. With a rapid intake of water, the seahorse sucks the prey up into its long snout (6). The most distinctive and arguably the most interesting feature of seahorse biology is the manner in which they reproduce. During mating, the female deposits a clutch of eggs into a pouch in the male's tail, where they are fertilised by the male. The male then seals the pouch shut, enclosing the embryos in a protective environment in which the developing seahorses are supplied with oxygen through a network of capillaries. At the end of pregnancy, the male enters labour, which lasts for hours as the male actively forces the young out of the pouch. Immediately after birth, the young seahorses are independent and receive no further care from either parent (6).

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Description

Named after the spines that project from the corners of the bony plates covering the body (4), the spiny seahorse is, like all seahorses, an intriguing and peculiar-looking fish. As well as its spiny appearance, this seahorse can be distinguished by its very long snout (2), which is sparsely patterned with white bars (5). The colour of this seahorse is highly variable, ranging from bright yellow to pale pink or green to match its surroundings (2) (5), and the spines often have dark tips (2). Its independently-moving eyes, which enable the seahorse to scan the surrounding water for potential prey (6), only add to this animal's bizarre appearance.

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Comprehensive Description

Biology

A rare inhabitant of shallow sheltered reefs, found among clumps of algae or in seagrass beds. Large adult pelagic and probably associated with drifting debris. Associated with sponges and sea-squirts (Ref. 30915, 58302). Ovoviviparous (Ref. 205). Feeds on zooplanktons and small crustaceans (Ref. 89972). The male carries the eggs in a brood pouch which is found under the tail (Ref. 205). Use in traditional Chinese medicine is increasing with the rise in patent medicines (Ref. 30915). Not common in the aquarium trade (Ref. 30915).

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Biology

A rare inhabitant of shallow sheltered reefs, found among clumps of algae or in seagrass beds. Large adult pelagic and probably associated with drifting debris. Associated with sponges and sea-squirts (Ref. 30915, 58302). Ovoviviparous (Ref. 205). The male carries the eggs in a brood pouch which is found under the tail (Ref. 205). Use in traditional Chinese medicine is increasing with the rise in patent medicines (Ref. 30915). Not common in the aquarium trade (Ref. 30915).

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Distribution

Indo-Pacific: Tanzania and South Africa to Hawaii and Tahiti, north to Japan, south to New Caledonia. Reported from the Arafura Sea (Ref. 9819). This name is used for at least four distinct species (Ref. 30915). International trade is monitored through a licensing system (CITES II, since 5.15.04) and a minimum size of 10 cm applies.

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Ecology

Habitat

Habitat and Ecology

Hippocampus histrixis often found at depths between six and 20 m (Lourie et al. 2004) but may also be found deeper than this (Kuiter 2000). This species is found on a variety of substrates including sponges, weedy rocky reefs, soft corals but mainly on seagrass beds (Lourie et al. 2004, Kuiter 2000).

All seahorse species have vital parental care, and many species studied to date have high site fidelity (Perante et al. 2002, Foster and Vincent 2004), highly structured social behaviour (Vincent and Sadler 1995), and relatively sparse distributions (Lourie et al. 1999) - all traits which make seahorses vulnerable to exploitation. There are however some traits, such as small body size, fast growth and high fecundity that may make seahorses more resilient to exploitation (Morgan 2007). However a specialised life-history coupled with a dependence on shallow habitats that are subject to extremely high fishing pressure, and the fact that seahorses do not move very much and are thus easily captured, means they are very vulnerable to over-exploitation. The importance of life history parameters in determining response to exploitation has been demonstrated for a number of species, including seahorses (Jennings et al. 1998, Foster and Vincent 2004).

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Habitat: reef-associated. A rare inhabitant of shallow sheltered reefs, found among clumps of algae or in seagrass beds. Large adults occur pelagically and are probably associated with drifting debris.

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Found at depths of at least six metres, the spiny seahorse is often found in water over soft bottoms, amongst soft coral, sponges and sea squirts (2) (5), where there is little or no seagrass (2). It may also be found in shallower areas where algae grow on reef rubble (dead, unstable, coral) (5).

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IUCN Red List Assessment

Hippocampus histrix was previously listed as Data Deficient but new information from trade surveys, and international trade data made available since the listing of seahorses on Appendix II of CITES in 2004, has allowed us to suspect a population decline of at least 30% over the last 1015 years and that these declines are suspected to continue into the future. There are also concerns about habitat destruction and capture of seahorses as bycatch throughout the range of H. histrix. For these reasons, this species is listed as Vulnerable under criterion A.

Using data from the CITES Trade Database, it was found that this species is widely traded in both the live and dry trade throughout it's range and that trade iscontinuing (Evanson et al. 2011, UNEP-WCMC 2012a). Historical trade surveys report trade in this species from the mid 1990's in various parts of its global range(McPherson and Vincent 2004, Meeuwiget al.2006, Perryet al.2010)and even at this stage, interviews with fishers and traders reported declines in availability of seahorses in some countries(McPherson and Vincent 2004, Perryet al.2010). Together this information demonstrates that there has been substantial pressure on wild populations for well over 10 years and that these pressures are continuing.

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Trends

Population

There is little information on population levels and trends for Hippocampus histrixbut it can be suspected that population levels are decreasing due to exploitation for international trade, coupled with high levels of bycatch and habitat destruction of H. histrix's primary habitat, seagrasses.

In parts of its range fishers and traders have reported declines in the availability and/or size of seahorses. For example, in 1998 and 1999 in Malaysia and Thailand, surveys of both fishers and traders reported declines in the availability of seahorses includingH. histrix(Perryet al.2010).There are also reports of general seahorse declines in the Philippines (O'Donnelet al.2010). In East Africa, surveys of fishers and traders in 2000 documented declines in seahorse availability and size, which includedH. histrix(McPherson and Vincent 2004). Currently, trade in this species is extensive with annual reported volumes exceeding 200 thousand individuals annually between 2004 and 2010 from a number of countries throughout this species' range (Evanson et al. 2011, UNEP-WCMC 2012a). Trade in seahorses,is expected to continue into the future as the demands for traditional medicines increase due to their increasing popularity in both the developed and developing world (Robinson and Zhang 2011).

General seahorse population declines within H. histrix's range are suspected as a result of habitat degradation and declines in seagrasses (Marcus et al. 2007, Short et al. 2011), and mortality from intense trawling bycatch (Baum et al. 2003, Giles et al. 2006, Perry et al. 2010) - and indeed these threats are known to occur throughout this species' range (FAO 2001, Perry et al. 2010).

Since trade is reported for several different parts of this species' range and that the threats facing this species occur throughout its range, it is suspected that these declines areoccurringglobally forH. histrix. It is conservatively suspected that the rate of decline has been at least 30% for the past 1015 years and that this decline is expected to continue into the future.

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Threats

The major threat to Hippocampus histrix is international trade for the aquarium and traditional medicine trades. To supply this trade, this species is caught in both targeted fisheries as well as bycatch in other non-selective fisheries, particularly shrimp trawls(McPherson and Vincent 2004, Meeuwig et al. 2006, Perryet al.2010).H. histrix has been reported in international trade since the mid 1990's and even at this stage, interviews with fishers and traders reported declines in the availability of seahorses (McPherson and Vincent 2004, Perry et al. 2010).

Even without demand for trade, this species is known to be a bycatch in the tropical shrimp trawl fishery and shrimp trawling is known to occur throughout much of its range and cause substantial damage to this species' habitats (FAO 2001, Perry et al. 2010).

Indeed, this species' in-shore seagrass habitats are threatened throughout its range (Short et al. 2011). Major threats faced by seagrasses include; eutrophication, sedimentation, coastal construction, dredging and invasive species and these threats result in decline in and fragmentation of seagrass habitats (see Short et al. 2011 for an overview of threats facing seagrasses). It is reasonable to expect that all of these threats will continue into the future.

Seahorses life history and ecological traits may increase their susceptibility to these threats (see Habitats and Ecology).

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Many seahorses are threatened by exploitation for use in traditional Chinese medicines, as well as for curios, souvenirs and aquariums (7). Although the spiny seahorse is known to be collected (5), it is less desirable than some other species for the traditional Chinese medicine trade and is rarely seen in the aquarium trade (2). There is insufficient information to determine to what extent this species may currently be threatened by any such activities, and thus the IUCN has classified the spiny seahorse as Data Deficient (1).

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Management

Conservation Actions

AllHippocampusspecies are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This means that countries who are signatories to CITES are subject to regulations on the export of seahorses. Countries are required to provide permits for all exports of seahorses and are meant to provide evidence that these exports are not detrimental to wild populations. However a lack of basic information on distribution, habitat and abundance means many CITES Authorities cannot assess sustainability of their seahorse exploitation and meet their obligations to the Convention. The challenge is particularly large in that most seahorses entering trade are caught incidentally as bycatch and thus imposing export quotas would achieve next to nothing for wild populations.

CITES has recommended a minimum size limit of 10 cm height for all seahorse specimens in trade (CITES Decision 12.54). This limit represents a compromise between the best biological information available at the time of listing and perceived socioeconomic feasibility. But we urgently need information on wild populations to assess their conservation status and take conservation action, as well as refine management recommendations. For example, evidence on variation in the spatial and temporal abundance of seahorses would enable areas of high seahorse density to be identified, as the basis for considering area restrictions on non-selective fishing gear that obtainsHippocampusspecies as bycatch. An understanding of the technical and logistical feasibility of returning to the sea live seahorses taken as bycatch in various types of fishing gear would provide the basis for considering the feasibility of minimum size limits and/or other output controls. Establishing monitoring program of landings of seahorses at representative sites, taking into account different gear types and means of extraction and recording catch and effort metrics would allow us to assess population conservation status and develop management recommendations for various fishery types.

Hippocampus histrix has been listed as Data Deficient in the Vietnamese Red Data Book.

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Conservation

The spiny seahorse is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) meaning that any trade in this species should be carefully monitored (3). It has been recommended that further research is undertaken on this little-known seahorse (1).

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Wikipedia

Spiny seahorse

The spiny seahorse (Hippocampus histrix), also referred to as the thorny seahorse, is a seahorse in the family Syngnathidae (seahorses and pipefishes) of the order Syngnathiformes. H. histrix is found in seagrass beds as well as weedy or spongy reefs in the Indo-Pacific and has one of the largest species ranges of any seahorse. It occasionally makes its way into the aquarium trade. It grows to a size of 17 cm in length.

H. histrix is listed as vulnerable by both the IUCN[1] and the Viet Nam National Red Data Book. Trade of this species is limited under CITES, requiring licenses and a minimum size limit to be met. Like many other species of seahorse, H. histrix is increasingly threatened by traditional and patented Chinese medicine.